Re: IntegerBox not restricting input to integers in GWT 2.4.0

I implemented a filter that stop users entering the wrong thing.  I figured if TextBox.setMaxLength does it, then why not.

However, as Thomas pointed out, it's hard to do properly.  I ended up allowing the invalid input and then removing it in a scheduleDeferred command.  Not ideal as the user sees the invalid input flash up, but it at least works on all browsers.

On Saturday, April 21, 2012 4:48:06 AM UTC+10, Alfredo Quiroga-Villamil wrote:

@Jen:

Your code and something along the lines to what you proposed would certainly work and be flexible enough.

@Andrei:

"When a user presses a button and nothing happens, many users would assume
that your app is broken (they did press a letter for some reason!)"

You always know when/what the user typed. The app would not look broken if upon the keydown and read of the key you know that it doesn't meet the specification and right away let the user know that "You can only type xxxx here"

Alfredo

On Fri, Apr 20, 2012 at 2:38 PM, Jens <jens.nehlmeier@gmail.com> wrote:

I always try to keep in mind that GWT is a tool kit. However, when a class is named IntegerBox, to be used in a UI, yeah I expect it to be type safe and also do what its name implies in the UI as well as programmatically. In this case only allow Integers to be typed in.

Some years ago when doing ordinary desktop applications I would probably expect the same. But today developing web applications my mind shifted and I found it more important to be liberal on the user input but tell the user if they have done something wrong. This just feels more like things work on the web and I want to preserve this feeling even in web applications because thats what people are used to when using the web.

Also inexperienced users may think their keyboard is somehow broken if nothing happens when typing a letter into an input box because its just so uncommon on the web to swallow user input.

In any case, I'll hang on to this email and instead of talking more, perhaps when I have some free time I'll just get to it and see if I can add the implementation for it, test it across browsers and submit it for a patch review. No promises since I am really busy these days, but we'll see.

Maybe it can be as easy as:

IntegerBox() {

 this(false); //makes sure that, by default, you get the same behavior as of today

}

IntegerBox(bolean strictMode) {

 super(Document.get().createInputElement(), IntegerRenderer.instance(), IntegerParser.instance(), strictMode ? IntegerInputValidator.instance() : null);

}

along with an additional constructor in ValueBox -> ValueBoxBase taking the input validator. If an input validator is present, ValueBoxBase attaches a key handler and routes key events through the validator (which can decide to swallow the key). That way you can opt-in to your desired behavior (you dont change behavior of existing apps) and you pretty much only have to implement input validators.

 

Appreciate the responses.

You are welcome 

-- J.

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Alfredo Quiroga-Villamil

AOL/Yahoo/Gmail/MSN IM:  lawwton

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